1. Field of the Invention
This invention concerns a drilling tool for sinking wells in underground rock formations, where the direction for drilling can be selected.
2. State of the Art
In a known version of such a drilling tool, a sealed hydraulic system with a hydraulic reservoir and a hydraulic pump is accommodated in the drilling tool to act on force-transmitting elements. The force-transmitting elements act on control runners that are pressed against the wall of the borehole.